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Plastic Optical Materials

Date post: 13-Jan-2016
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Plastic Optical Materials. Sheng-Huei Derek Lu College of Optical Sciences University of Arizona. Apple iPhone 4 Camera Lens. Apple iPhone 4 Camera Specs: 5.0 Mpixels (2592 x 1936) 3.85 mm lens focal length f/2.8 lens aperture Equivalent 35mm film camera 30 mm f/22 - PowerPoint PPT Presentation
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Plastic Optical Materials Sheng-Huei Derek Lu College of Optical Sciences University of Arizona
  • Plastic Optical MaterialsSheng-Huei Derek Lu

    College of Optical SciencesUniversity of Arizona

  • Apple iPhone 4 Camera LensApple iPhone 4 Camera Specs:5.0 Mpixels (2592 x 1936)3.85 mm lens focal lengthf/2.8 lens apertureEquivalent 35mm film camera30 mm f/22

    Sample image is 2592x1936 pixels (5.0 MP, 4.02:3)

    Don't throw away your FourThird, APS-C or full frame SLR Cost is Everything!!

  • iPhone 4 Camera ModuleGlass cell phone lenses cost $20-$40 in the market.Plastic cost: $3.55 only

    Manufacturer: Largan Precision Co., LTD, TaiwanProduct#: 9457FComposition4 Plastic Elements

    Very high production volumesInjection Molding: 8-Holes Method8 cavities at the same time

    Monthly volume = 207,306 parts

  • OutlinesPlastic optical material applicationAdvantagesDisadvantagesIssues:Structural StabilityThermal StabilityMoisture AbsorptionInjection MoldingWavefont error budgetReference

  • What are optical elements made of plastic?Cellphone/ NB/ Car/ Camera LensBar code scanners in CD playersPrismsLED collimatorDiffractive Optical Elements

  • Main AdvantagesCostProduction volumeWeight reductionAspheric and diffractive surfacesIntegral features can have mounting features or multifunction parts

  • DisadvantagesLower service temperature than glass - max service 80-130 CLow structural stability - soft, larger deflection while applying force, lower resonant frequency than glassPoor thermal properties high dn/dT, high CTEMoisture AbsorptionLimited material selection

  • Material Properties of Plastic Optical Element

  • Plastic Element Structural Stability = 1 g/cm3, E = 3 Gpa (glass: =2.5 g/cm3, E=80 Gpa)Resonant frequency

    Plastic with 1/3 resonant frequency than glassDeflection per thickness

    Plastic with 10 times deflection than glass

  • Plastic Element Thermal Stabilitydn/dT = -8.5 ppm/C, CTE = 72 ppm/C, = 0.21 W/mK (glass: dn/dT = 1.86 ppm/C, CTE = 7 ppm/C, = 1 W/mK)Defocus due to one degree change

    = 89 ppm/C for plastic, = 3.28 ppm/C for glassLinear thermal distortion of a constant heat flux

    Plastic with 50 times thermal deflection than glass

  • Moisture Absorption Water absorption: change of volume, change of refractive indexThe coefficient of moisture expansion (CME) for PMMA is about 0.5%The change of refractive index for PMMA is about 900 ppm

    Cycloolefin Polymer (COP) and Cycloolefin Copolymer (COC) are known as low moisture absorption.

  • Injection Molding

    Surface Imperfections - Melt temperature is too high to cause gas evolution: bubbles - Pressure is too low to cause incomplete filling of mold.Shrinkage - If the part thickness is too thin, part will shrink while cooling. - Applying holding pressure is maintained to compensate for material shrinkage

  • Tolerance Analysis: wavefont error budget for the plastic optical component

    1 mold costs $200,000!

  • ReferenceSelected plastic optical material characteristics are listed in my tutorial: Tutorial for Plastic Optical Materials

    Great reference book: Stefan Bumer etc. Hand Book of Plastic Optics, 2005 WILEY

    Formulas: Prof. Burge, Opti 521/421 class note